In Reply to: Does our BMW Run faster when Heater is fully on? posted by Chad on December 08, 1999 at 23:29:50:
: Just wondering.... Any reliable sources??
: Thank you in advance.
Turning the heater on will have no effect on the engine. By turning the heater on you're simply redirecting a portion of the heat dissipation from the radiator to the heater core. Unlike A/C, heat is "free" since the engine has to produce heat to run. The only load on the alternator from heating would be the fan motor. If you cranked the fan up from 1 to 3 that would put a very slight additional load on the alternator and engine but if you don't change the fan speed when you turn the temperature knob up, there is no effect on the engine.